School of Pharmacy, Guangdong Pharmaceutical University, Guangzhou 510006, China.
Food Funct. 2018 Jul 17;9(7):3997-4007. doi: 10.1039/c8fo00790j.
Psidium guajava fruit is a subtropical fruit, functional food and traditional medicine for the adjuvant treatment of diabetes mellitus in China. To investigate the active components responsible for its health benefits, a novel heteropolysaccharide GP70-3 was purified by water extraction, ethanol precipitation and column chromatography. Structural characterization of GP70-3 was elucidated for the first time by monosaccharide composition assay, Fourier transform-infrared spectroscopy (FT-IR), methylation analysis, gas chromatography coupled with mass spectrometry (GC-MS) and nuclear magnetic resonance spectroscopy (NMR). The data revealed that GP70-3 contained a backbone of 1→3,6)-linked β-d-Galp, 1→5)-linked α-l-Araf, 1→6)-linked β-d-Galp and 1→3)-linked β-d-Galp, branched with 1→2,3,5)-linked α-l-Araf, 1→3)-linked α-l-Araf, 1→3)-linked α-l-Rhap, 1→3)-linked β-d-GlcpA, 1→3)-linked β-d-GalpA and terminated with →1)-linked β-d-Galp. Advanced structure studies showed GP70-3 consisted of irregular flakes with rounded-spherical pores. Moreover, GP70-3 exhibited outstanding α-glucosidase inhibitory activity in vitro, with an IC50 value of 2.539 ± 0.144 μM, which was 1867 times higher than that of the positive control acarbose (IC50 value of 4.744 ± 0.026 mM). Therefore, consumption of guava polysaccharides may be beneficial as an α-glucosidase inhibitor for reducing the postprandial blood glucose level and treating type II diabetes.
番石榴果是一种亚热带水果，在中国被作为功能性食品和传统药物用于辅助治疗糖尿病。为了研究其具有健康益处的活性成分，我们通过水提、醇沉和柱层析等方法从番石榴中提取并纯化得到一种新型杂多糖 GP70-3。我们首次通过单糖组成分析、傅里叶变换红外光谱（FT-IR）、甲基化分析、气相色谱-质谱联用（GC-MS）和核磁共振波谱（NMR）等方法对 GP70-3 的结构进行了表征。数据表明，GP70-3 的糖链由 1→3,6)-β-d-Galp、1→5)-α-l-Araf、1→6)-β-d-Galp 和 1→3)-β-d-Galp 组成，以 1→2,3,5)-α-l-Araf、1→3)-α-l-Araf、1→3)-α-l-Rhap、1→3)-β-d-GlcpA、1→3)-β-d-GalpA 为支链，以→1)-β-d-Galp 为末端。高级结构研究表明，GP70-3 由不规则片状物组成，具有圆形球形孔。此外，GP70-3 在体外表现出出色的α-葡萄糖苷酶抑制活性，IC50 值为 2.539±0.144μM，比阳性对照阿卡波糖（IC50 值为 4.744±0.026mM）高 1867 倍。因此，食用番石榴多糖可能作为一种α-葡萄糖苷酶抑制剂有益于降低餐后血糖水平并治疗 II 型糖尿病。
